The second filter collects PM2.5-0 particles is also a 47 mm diameter Nucleopore polycarbonate filter but with a pore size of 0.4 μm. Note that the PM2.5-0 Nucleopore filters are not coated with Apiezon.
Figures 4 and 5 show scanning electron microscopy (SEM) images of coarse and fine Nucleopore polycarbonate filters on which air particulate matter from the Wellington region, New Zealand, have been caught. The pores appear as black holes in the image.
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